Konbanwa!
I've noticed that my 505 takes a couple of hours to charge
when plugged into the USB port of my computer, with the red light staying on the entire time.
The other day I bought a couple of different chargers for the PSP that were recommended to me quite cheaply (for Japan, anyway. ¥600 & ¥950) One is for the regular charging port and one is an AC-to-USB charger. Some folks say that the AC-to-USB doesn't work for the 505. Someone else here said it worked for them. The clerk at the store 'thought' it would work but wasn't sure. I'll be testing it over the weekend. However, when either of them are plugged into the 505 and the source, the red light is glowing brightly. If your little red light is out, it sounds as if Tinkerbell isn't feeling so healthy....
Stitchawl